1. Field of the Invention
The present invention relates to an idle air control device, in which idle air is controlled by a valve body operated by a valve body driving mechanism, bypasses a throttle valve, and is supplied to an intake passage at the downstream side from the throttle valve through a bypass air passage. More particularly, the present invention relates to the idle air control device in a multiple throttle body, in which a plurality of throttle bodies having intake passages through the insides thereof are provided, and the idle air controlled by a single valve body is supplied toward the respective intake passages through respective bypass air passage.
2. Description of the Conventional Art
One example of an idle air control device in a throttle body is indicated in Japanese Patent Application Laid Open No. 11-201004.
According to this idle air control device, an intake passage is provided through a throttle body, a bypass air passage is formed so as to by pass a throttle valve for opening and closing the intake passage, and the downstream side of the bypass air passage is opened in the intake passage at the downstream side from the throttle valve.
Further, a valve seat is formed in the bypass air passage, and the valve seat is controlled to be opened and closed by a valve body which is provided facing the valve seat and has a taper-shaped control valve part. Further, the valve body is operated by a valve body driving mechanism such as a stepping motor or the like.
Thus, when the valve body is operated by the valve body driving mechanism, the valve body is displaced corresponding to the stroke of the valve body driving mechanism, and the control valve part controls an opening area of the valve seat. The idle air corresponding the opening of the valve seat is supplied to the intake passage at the downstream side from the throttle valve so as to carry out an idle operation of an engine. Such the device is referred to as a single opening control type idle air control device.
Further, one more example of an idle air control device in a throttle body is indicated in Japanese Patent Application Laid Open No. 2002-89415. According to this device, the device comprises a plurality of intake passages, and the respective intake passages are controlled to be opened and closed by respective throttle valves. On the other hand, a plurality of bypass air passages, which communicate with the intake passages at the downstream side from the respective throttle valves, are opened on a side wall of a cylindrical valve body storage chamber. Such the openings are movably provided in the valve body storage chamber, and the opening is controlled to be opened and closed by an outside wall of a cylindrical single plunger operated by a valve body driving mechanism. Then, idle air corresponding to the opening is supplied to the intake passages at the downstream side from the throttle valves of the respective intake passages through the respective bypass air passages, so as to carry out an idle operation of an engine. Such the device is referred to as a plural openings control type idle air control device.